This SBIR Phase II revision proposal requests $175,000 of additional funding for the Chromatan Corporation to commercialize the Continuous Countercurrent Tangential Chromatography (CCTC) technology for the purification of high value biological products, e.g., monoclonal antibodies for the treatment of different types of cancers, Rheumatoid Arthritis, Crohn's, Multiple Sclerosis and other serious diseases. The funding will be used in order to develop and commercialize a unique chromatography resin that will be specifically suited for the CCTC system. This development will enable drug manufacturers to decrease the overall capture purification costs by over 65% when compared with traditional column chromatography saving drug manufacturers $500,000 - $3,000,000 per clinical campaign depending on batch size. Downstream processing currently accounts for as much as 80% of the overall cost of production of recombinant protein products. CCTC overcomes many of the limitations of conventional column chromatography by using resin particles in the form of a slurry, which is pumped through a disposable flow path consisting of a series of static mixers and hollow fiber membrane modules. The CCTC system eliminates column packing and has a fully disposable flow path that is easily scalable for processing bioreactor effluents from large scale clinical campaigns. This revised proposal is focused on development of a custom resin specifically designed for CCTC. This resin will have a smaller particle size (10 - 20 ?m), leading to much faster binding kinetics, as well as higher dynamic binding capacity. This development will have the following favorable impacts on the performance of the CCTC system: 1. Increase the productivity of the CCTC system for mAb purification from cell culture fluid by an additional four-fold (compared to that obtained using 45 ?m resin particles). 2. Reduce buffer consumption requirements and increase the product mAb concentration by at least 50% in comparison with the current CCTC system. 3. Increase the yield of mAb to ?95% from existing 85-90%. 4. Decrease the mAb purification cost by ~50% in comparison with the current CCTC system using 45 ?m particles.